Security provided by wireless telephony service providers is often inadequate for subscribers' needs. Wireless communications are by definition broadcast and therefore accessible to anyone with an appropriate radio frequency (RF) receiver. A malicious eavesdropper need not perform a wiretap or even position himself in close proximity with a legitimate participant in the target conversation. There is therefore a special need for security in wireless telephony.
A wireless telephony subscriber today must rely on the security measures taken by the wireless service provider. Those service providers often provide weak or no encryption, particularly where a call must be handed off between cells managed by different wireless service providers. Because such cell handoff regions are geographically fixed, wireless connections in those regions are particularly vulnerable targets.
Encryption techniques useable on wireless communications systems are available today. For example, the developing 802.11x wireless local area network standard specifically provides for encryption of digital communications transmitted over an RF carrier. Further, virtual private network (VPN) technology may be used to establish a secure digital connection over a path that includes a wireless link. Each of those techniques, however, requires processing power at both ends of the connection sufficient to conduct an encrypted communications session, in addition to digital coding of the voice signal (if the connection is to be used for voice). While those solutions are now commonly used for digital data communications in which laptops or other devices containing powerful processors are available at both ends of the connection, a VPN or other encrypted connection is not a practical solution for telephony because a called land line party is most likely using a simple telephone set that is not capable of conducting an encrypted session, or even of encoding the voice data in digital form. Even handheld wireless telephones with digital capability typically do not have processing capability available for conducting a strongly encrypted communication session. Those handheld wireless telephones that can perform some sort of encryption are generally dedicated to the encryption system of the wireless services provider, and do not support user-initiated encryption.
Handheld wireless communication devices having stronger processing capacity, while not widespread, are becoming more common. For example, devices similar to a personal digital assistant (PDA) are available today with a speaker, microphone and radio transceiver, capable of emulating a wireless telephone, and capable of uploading software. While those devices may be programmed to conduct secure, encrypted sessions, as noted above, those sessions, under today's technology, may be conducted only with other, similarly-configured devices. In the case of a secure telephone conversation, a user of such a PDA would be capable of calling only similarly-equipped users.
U.S. Pat. No. 6,084,969 to Wright et al. describes an encryption system for a pager network. The encryption system includes a proxy that receives and decrypts messages from a sending pager, and then re-encrypts the message with a new session key and transmits it to the receiving pager. Both pagers must be configured to use the encryption system.
There is presently a need for a method and system that can provide secure communications capability for a mobile telephony subscriber. Specifically, the method and system should function without the need for compatible encryption capability at both ends of the call. To the inventors' knowledge, there is no such system or method currently employed to satisfactorily accomplish that task.